1. Field of the Invention
The present invention relates to an ink density adjusting mechanism and an electrophotographic apparatus using this ink density adjusting mechanism, and more particularly to an ink density adjusting mechanism for use in an electrophotographic process using liquid ink and an electrophotographic apparatus equipped with this ink density adjusting mechanism.
2. Description of the Related Art
Conventionally, a transmission-type sensor, with a light-emitting device and a light-receiving device as the density detecting means, has been used on an electrophotographic apparatus using liquid ink to keep the ink density at a constant level. This technology is disclosed, for example, in FIGS. 1-4 of Japanese Patent Laid-Open Publication No. Hei 8-314283.
To quickly start printing at a right density the next time printing is to start, it is an effective way to sense the ink density after printing and then adjust the ink density at a right density. A transmission type density sensor, though simple in circuit configuration, requires ink to be circulated for sensing the correct density. Circulating ink for density adjustment after printing, that is, at non-print time, means that ink must be supplied also to a developing unit and that stains are sometimes generated on a photo-sensitive medium on which images are to be developed.
As described above, the conventional ink density adjusting mechanism circulates ink at non-print time in order to adjust the density. One of the problems with this mechanism is that, because ink is circulated also to the developing unit, stains are sometimes generated on a photo-sensitive medium on which images are to be developed.